Atomic layer deposition process

ABSTRACT

In one embodiment, a method for depositing a material on a substrate during an atomic layer deposition (ALD) process is provided which includes positioning the substrate on a substrate support within a process chamber, flowing a carrier gas into an expanding channel to form a circular flow of the carrier gas, exposing the substrate to the circular flow, pulsing a first reactant gas into the circular flow, and depositing a material onto the substrate. The method further provides that the process chamber has a chamber lid containing a centrally positioned expanding channel, a tapered bottom surface extending from the expanding channel to a peripheral portion of the chamber lid, at least two gas inlets in fluid communication with the expanding channel, and at least two conduits positioned to provide a gas flow having a circular pattern within the expanded channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 11/077,753(APPM/005192.C1), filed Mar. 11, 2005, which is a continuation of U.S.Ser. No. 10/032,284 (APPM/005192.02), filed Dec. 21, 2001, and issued asU.S. Pat. No. 6,916,398, which claims benefit of U.S. Ser. No.60/346,086 (APPM/005192L), filed Oct. 26, 2001, which are hereinincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to an apparatus and methodfor vapor deposition, and more particularly, embodiments relate toatomic layer deposition (ALD) processes.

2. Description of the Related Art

Reliably producing submicron and smaller features is one of the keytechnologies for the next generation of very large scale integration(VLSI) and ultra large scale integration (ULSI) of semiconductordevices. However, as the fringes of circuit technology are pressed, theshrinking dimensions of interconnects in VLSI and ULSI technology haveplaced additional demands on the processing capabilities. The multilevelinterconnects that lie at the heart of this technology require preciseprocessing of high aspect ratio features, such as vias and otherinterconnects. Reliable formation of these interconnects is veryimportant to VLSI and ULSI success and to the continued effort toincrease circuit density and quality of individual substrates.

As circuit densities increase, the widths of vias, contacts, and otherfeatures, as well as the dielectric materials between them, decrease tosubmicron dimensions (e.g., about 0.20 micrometers or less), whereas thethickness of the dielectric layers remains substantially constant, withthe result that the aspect ratios for the features, i.e., their heightdivided by width, increase. Many traditional deposition processes havedifficulty filling submicron structures where the aspect ratio exceeds4:1, and particularly where the aspect ratio exceeds 10:1. Therefore,there is a great amount of ongoing effort being directed at theformation of substantially void-free and seam-free submicron featureshaving high aspect ratios.

Atomic layer deposition is one deposition technique being explored forthe deposition of material layers over features having high aspectratios. One example of atomic layer deposition comprises the sequentialintroduction of pulses of gases. For instance, one cycle for thesequential introduction of pulses of gases may comprise a pulse of afirst reactant gas, followed by a pulse of a purge gas and/or a pumpevacuation, followed by a pulse of a second reactant gas, and followedby a pulse of a purge gas and/or a pump evacuation. The term “gas” asused herein is defined to include a single gas or a plurality of gases.Sequential introduction of separate pulses of the first reactant and thesecond reactant may result in the alternating self-limiting absorptionof monolayers of the reactants on the surface of the substrate and,thus, forms a monolayer of material for each cycle. The cycle may berepeated to a desired thickness of the deposited material. A pulse of apurge gas and/or a pump evacuation between the pulses of the firstreactant gas and the pulses of the second reactant gas serves to reducethe likelihood of gas phase reactions of the reactants due to excessamounts of the reactants remaining in the chamber.

However, there is a need for processes to perform gas delivery and toperform deposition of films by atomic layer deposition.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to an improved gas deliveryapparatus adapted for atomic layer deposition or rapid chemical vapordeposition. One embodiment of the gas delivery assembly comprises acovering member having an expanding channel at a central portion of thecovering member and having a bottom surface extending from the expandingchannel to a peripheral portion of the covering member. One or more gasconduits are coupled to the expanding channel in which the one or moregas conduits are positioned at an angle from a center of the expandingchannel.

Another embodiment of the gas delivery assembly comprises a first valveand a second valve. The first valve includes a first delivery line and afirst purge line. The first delivery line comprises a first reactant gasinlet, a first reactant gas outlet, and a first valve seat assembly. Thefirst purge line comprises a first purge gas inlet and a first purge gasoutlet. The first purge gas outlet of the first purge line is incommunication with the first delivery line downstream of the first valveseat assembly. The second valve includes a second delivery line and asecond purge line. The second delivery line comprises a second reactantgas inlet, a second reactant gas outlet, and a second valve seatassembly. The second purge line comprises a second purge gas inlet and asecond purge gas outlet. The second purge gas outlet of the second purgeline is in communication with the second delivery line downstream of thesecond valve seat assembly.

One embodiment of a chamber comprises a substrate support having asubstrate receiving surface. The chamber further includes a chamber lidhaving a passageway at a central portion of the chamber lid and atapered bottom surface extending from the passageway to a peripheralportion of the chamber lid. The bottom surface of the chamber lid isshaped and sized to substantially cover the substrate receiving surface.One or more valves are coupled to the passageway, and one or more gassources are coupled to each valve. In one aspect, the bottom surface ofthe chamber lid may be tapered. In another aspect, a reaction zonedefined between the chamber lid and the substrate receiving surface maycomprise a small volume. In still another aspect, the passageway maycomprise a tapered expanding channel extending from the central portionof the chamber lid.

Another embodiment of the chamber comprises a substrate support having asubstrate receiving surface. The chamber further comprises a chamber lidhaving an expanding channel extending from a central portion of thechamber lid and having a tapered bottom surface extending from theexpanding channel to a peripheral portion of the chamber lid. One ormore gas conduits are disposed around an upper portion of the expandingchannel in which the one or more gas conduits are disposed at an anglefrom a center of the expanding channel. A choke is disposed on thechamber lid adjacent a perimeter of the tapered bottom surface.

One embodiment of a method of depositing a material layer over asubstrate structure comprises delivering a first reactant gas and afirst purge gas through a first gas conduit in which the first reactantgas is provided in pulses and the first purge gas is provided in acontinuous flow. The method further comprises delivering a secondreactant gas and a second purge through a second gas conduit in whichthe second reactant gas is provided in pulses and the second purge gasis provided in a continuous flow.

One embodiment of a method of delivering gases to a substrate in asubstrate processing chamber comprises providing one or more gases intothe substrate processing chamber, reducing a velocity of the gasesthrough non-adiabatic expansion, providing the gases to a centralportion of the substrate, and directing the gases radially across thesubstrate from the central portion of the substrate to a peripheralportion of the substrate.

Another embodiment of a method of delivering gases to a substrate in asubstrate processing chamber comprises providing one or more gases to acentral portion of the substrate and directing the gases radially at asubstantially uniform velocity across the substrate from the centralportion of the substrate to a peripheral portion of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic cross-sectional view of one embodiment of achamber including a gas delivery apparatus adapted for atomic layerdeposition.

FIG. 2 is a top cross-sectional view of one embodiment of the expandingchannel of the chamber lid of FIG. 1.

FIG. 3 is a cross-sectional view of the expanding channel of the chamberlid of FIG. 1.

FIG. 4 is a schematic cross-sectional view illustrating the flow of agas at two different positions between the surface of a substrate andthe bottom surface of the chamber lid of FIG. 1.

FIG. 5 is a top cross-sectional view of another embodiment of theexpanding channel of the chamber lid which is adapted to receive asingle gas flow.

FIG. 6 is a top cross-sectional view of another embodiment of theexpanding channel of the chamber lid which is adapted to receive threegas flows.

FIG. 7 is a schematic cross-sectional view of another embodiment of achamber including a gas delivery apparatus adapted for atomic layerdeposition.

FIG. 8 shows another embodiment of a chamber including a gas deliveryapparatus adapted for atomic layer deposition.

FIG. 9A is a schematic cross-sectional view of one embodiment of thechoke of the chamber lid.

FIG. 9B is a cross-sectional view of another embodiment of the choke ofthe chamber lid.

DETAILED DESCRIPTION

FIG. 1 is a schematic cross-sectional view of one embodiment of achamber 200 including a gas delivery apparatus 230 adapted for atomiclayer deposition or rapid chemical vapor deposition. The term “atomiclayer deposition” and “rapid chemical vapor deposition” as used hereinrefer to the sequential introduction of reactants to deposit a thinlayer over a substrate structure. The sequential introduction ofreactants may be repeated to deposit a plurality of thin layers to forma conformal layer to a desired thickness. The chamber 200 may also beadapted for other deposition techniques.

The chamber 200 comprises a chamber body 202 having sidewalls 204 and abottom 206. A slit valve 208 in the chamber 200 provides access for arobot (not shown) to deliver and retrieve a substrate 210, such as a 200mm or 300 mm semiconductor wafer or a glass substrate, to and from thechamber 200.

A substrate support 212 supports the substrate 210 on a substratereceiving surface 211 in the chamber 200. The substrate support 212 ismounted to a lift motor 214 to raise and lower the substrate support 212and a substrate 210 disposed thereon. A lift plate 216 connected to alift motor 218 is mounted in the chamber 200 and raises and lowers liftpins 220 movably disposed through the substrate support 212. The liftpins 220 raise and lower the substrate 210 over the surface of thesubstrate support 212. The substrate support 212 may include a vacuumchuck (not shown), an electrostatic chuck (not shown), or a clamp ring(not shown) for securing the substrate 210 to the substrate support 212during processing.

The substrate support 212 may be heated to heat a substrate 210 disposedthereon. For example, the substrate support 212 may be heated using anembedded heating element, such as a resistive heater (not shown), or maybe heated using radiant heat, such as heating lamps (not shown) disposedabove the substrate support 212. A purge ring 222 may be disposed on thesubstrate support 212 to define a purge channel 224 which provides apurge gas to a peripheral portion of the substrate 210 to preventdeposition thereon.

A gas delivery apparatus 230 is disposed at an upper portion of thechamber body 202 to provide a gas, such as a process gas and/or a purgegas, to the chamber 200. A vacuum system 278 is in communication with apumping channel 279 to evacuate any desired gases from the chamber 200and to help maintain a desired pressure or a desired pressure rangeinside a pumping zone 266 of the chamber 200.

In one embodiment, the gas delivery apparatus 230 comprises a chamberlid 232. The chamber lid 232 includes an expanding channel 234 extendingfrom a central portion of the chamber lid 232 and a bottom surface 260extending from the expanding channel 234 to a peripheral portion of thechamber lid 232. The bottom surface 260 is sized and shaped tosubstantially cover a substrate 210 disposed on the substrate support212. The expanding channel 234 has gas inlets 236A, 236B to provide gasflows from two similar pairs of valves 242A/252A, 242B/252B, which maybe provided together and/or separately.

In one configuration, valve 242A and valve 242B are coupled to separatereactant gas sources but are preferably coupled to the same purge gassource. For example, valve 242A is coupled to reactant gas source 238and valve 242B is coupled to reactant gas source 239, and both valves242A, 242B are coupled to purge gas source 240. Each valve 242A, 242Bincludes a delivery line 243A, 243B having a valve seat assembly 244A,244B and each valves 252A, 252B includes a purge line 245A, 245B havinga valve seat assembly 246A, 246B. The delivery line 243A, 243B is incommunication with the reactant gas source 238, 239 and is incommunication with the gas inlet 236A, 236B of the expanding channel234. The valve seat assembly 244A, 244B of the delivery line 243A, 243Bcontrols the flow of the reactant gas from the reactant gas source 238,239 to the expanding channel 234. The purge line 245A, 245B is incommunication with the purge gas source 240 and intersects the deliveryline 243A, 243B downstream of the valve seat assembly 244A, 244B of thedelivery line 243A, 243B. The valve seat assembly 246A, 246B of thepurge line 245A, 245B controls the flow of the purge gas from the purgegas source 240 to the expanding channel 234. If a carrier gas is used todeliver reactant gases from the reactant gas source 238, 239, preferablythe same gas is used as a carrier gas and a purge gas (i.e., an argongas used as a carrier gas and a purge gas).

Each valve seat assembly 244A, 244B, 246A, 246B may comprise a diaphragm(not shown) and a valve seat (not shown). The diaphragm may be biasedopen or closed and may be actuated closed or open respectively. Thediaphragms may be pneumatically actuated or may be electricallyactuated. Examples of pneumatically actuated valves includepneumatically actuated valves available from Fujiken, Inc. and Veriflow,Corp. Examples of electrically actuated valves include electricallyactuated valves available from Fujiken, Inc. Programmable logiccontrollers 248A, 248B may be coupled to the valves 242A, 242B tocontrol actuation of the diaphragms of the valve seat assemblies 244A,244B, 246A, 246B of the valves 242A, 242B. Pneumatically actuated valvesmay provide pulses of gases in time periods as low as about 0.020seconds. Electrically actuated valves may provide pulses of gases intime periods as low as about 0.005 seconds. An electrically actuatedvalve typically requires the use of a driver coupled between the valveand the programmable logic controller.

Each valve 242A, 242B may be a zero dead volume valve to enable flushingof a reactant gas from the delivery line 243A, 243B when the valve seatassembly 244A, 244B is closed. For example, the purge line 245A, 245Bmay be positioned adjacent the valve seat assembly 244A, 244B of thedelivery line 243A, 243B. When the valve seat assembly 244A, 244B isclosed, the purge line 245A, 245B may provide a purge gas to flush thedelivery line 243A, 243B. In the embodiment shown, the purge line 245A,245B is positioned slightly spaced from the valve seat assembly 244A,244B of the delivery line 243A, 243B so that a purge gas is not directlydelivered into the valve seat assembly 244A, 244B when open. A zero deadvolume valve as used herein is defined as a valve which has negligibledead volume (i.e., not necessary zero dead volume).

Each valve pair 242A/252A, 242B/252B may be adapted to provide acombined gas flow and/or separate gas flows of the reactant gas and thepurge gas. In reference to valve pair 242A/252A, one example of acombined gas flow of the reactant gas and the purge gas comprises acontinuous flow of a purge gas from the purge gas source 240 throughpurge line 245A and pulses of a reactant gas from the reactant gassource 238 through delivery line 243A. The continuous flow of the purgegas may be provided by leaving the diaphragm of the valve seat assembly246A of the purge line 245A open. The pulses of the reactant gas fromthe reactant gas source 238 may be provided by opening and closing thediaphragm of the valve seat assembly 244A of the delivery line 243A. Inreference to valve pair 242A/252A, one example of separate gas flows ofthe reactant gas and the purge gas comprises pulses of a purge gas fromthe purge gas source 240 through purge line 245A and pulses of areactant gas from the reactant gas source 238 through delivery line243A. The pulses of the purge gas may be provided by opening and closingthe diaphragm of the valve seat assembly 246A of the purge line 245A.The pulses of the reactant gas from the reactant gas source 238 may beprovided by opening and closing the diaphragm of the valve seat assembly244A of the delivery line 243A.

The delivery lines 243A, 243B of the valves 242A, 242B may be coupled tothe gas inlets 236A, 236B through gas conduits 250A, 250B. The gasconduits 250A, 250B may be integrated or may be separate from the valves242A, 242B. In one aspect, the valves 242A, 242B are coupled in closeproximity to the expanding channel 234 to reduce any unnecessary volumeof the delivery line 243A, 243B and the gas conduits 250A, 250B betweenthe valves 242A, 242B and the gas inlets 236A, 236B.

In reference to FIG. 3, each gas conduit 250A, 250B and gas inlet 236A,236B may be positioned in any relationship to a longitudinal axis 290 ofthe expanding channel 234. Each gas conduit 250A, 250B and gas inlet236A, 236B are preferably positioned normal (in which +β, −β=90°) to thelongitudinal axis 290 or positioned at an angle +β or an angle −β (inwhich 0°<+β<90° or 0°<−β<90°) from the centerline 302A, 302B of the gasconduit 250A, 250B to the longitudinal axis 290. Therefore, the gasconduit 250A, 250B may be positioned horizontally normal to thelongitudinal axis 290 as shown in FIG. 3, may be angled downwardly at anangle +β, or may be angled upwardly at an angle −β to provide a gas flowtoward the walls of the expanding channel 234 rather than directlydownward towards the substrate 210 which helps reduce the likelihood ofblowing off reactants adsorbed on the surface of the substrate 210. Inaddition, the diameter of the gas conduits 250A, 250B may be increasingfrom the delivery lines 243A, 243B of the valves 242A, 242B to the gasinlet 236A, 236B to help reduce the velocity of the gas flow prior toits entry into the expanding channel 234. For example, the gas conduits250A, 250B may comprise an inner diameter which is gradually increasingor may comprise a plurality of connected conduits having increasinginner diameters.

Referring to FIG. 1, the expanding channel 234 comprises a channel whichhas an inner diameter which increases from an upper portion 237 to alower portion 235 of the expanding channel 234 adjacent the bottomsurface 260 of the chamber lid 232. In one specific embodiment, theinner diameter of the expanding channel 234 for a chamber adapted toprocess 200 mm diameter substrates is between about 0.2 inches and about1.0 inch, preferably between about 0.3 inches and about 0.9 inches, andmore preferably between 0.3 inches and about 0.5 inches at the upperportion 237 of the expanding channel 234 and between about 0.5 inchesand about 3.0 inches, preferably between about 0.75 inches and about 2.5inches, and more preferably between about 1.1 inches and about 2.0inches at the lower portion 235 of the expanding channel 234. In anotherspecific embodiment, the inner diameter of the expanding channel 234 fora chamber adapted to process 300 mm diameter substrates is between about0.2 inches and about 1.0 inch, preferably between about 0.3 inches andabout 0.9 inches, and more preferably between 0.3 inches and about 0.5inches at the upper portion 237 of the expanding channel 234 and betweenabout 0.5 inches and about 3.0 inches, preferably between about 0.75inches and about 2.5 inches, and more preferably between about 1.2inches and about 2.2 inches at the lower portion 235 of the expandingchannel 234. In general, the above dimension apply to an expandingchannel adapted to provide a total gas flow of between about 500 sccmand about 3,000 sccm. In other specific embodiments, the dimension maybe altered to accommodate a certain gas flow therethrough. In general, alarger gas flow will require a larger diameter expanding channel. In oneembodiment, the expanding channel 234 may be shaped as a truncated cone(including shapes resembling a truncated cone). Whether a gas isprovided toward the walls of the expanding channel 234 or directlydownward towards the substrate 210, the velocity of the gas flowdecreases as the gas flow travels through the expanding channel 234 dueto the expansion of the gas. The reduction of the velocity of the gasflow helps reduce the likelihood the gas flow will blow off reactantsadsorbed on the surface of the substrate 210.

Not wishing to be bound by theory, it is believed that the diameter ofthe expanding channel 234, which is gradually increasing from the upperportion 237 to the lower portion 235 of the expanding channel 234,allows less of an adiabatic expansion of a gas through the expandingchannel 234 which helps to control the temperature of the gas. Forinstance, a sudden adiabatic expansion of a gas delivered through thegas inlet 236A, 236B into the expanding channel 234 may result in a dropin the temperature of the gas which may cause condensation of the gasand formation of droplets. On the other hand, a gradually expandingchannel 234 according to embodiments of the present invention isbelieved to provide less of an adiabatic expansion of a gas. Therefore,more heat may be transferred to or from the gas, and, thus, thetemperature of the gas may be more easily controlled by controlling thesurrounding temperature of the gas (i.e., controlling the temperature ofthe chamber lid 232). The gradually expanding channel 234 may compriseone or more tapered inner surfaces, such as a tapered straight surface,a concave surface, a convex surface, or combinations thereof or maycomprise sections of one or more tapered inner surfaces (i.e., a portiontapered and a portion non-tapered).

In one embodiment, the gas inlets 236A, 236B are located adjacent theupper portion 237 of the expanding channel 234. In other embodiments,one or more gas inlets 236A, 236B may be located along the length of theexpanding channel 234 between the upper portion 237 and the lowerportion 235.

FIG. 2 is a top cross-sectional view of one embodiment of the expandingsection 234 of the chamber lid 232 of FIG. 1. Each gas conduit 250A,250B may be positioned at an angle a from the centerline 302A, 302B ofthe gas conduit 250A, 250B and from a radius line 304 from the center ofthe expanding channel 234. Entry of a gas through the gas conduit 250A,250B preferably positioned at an angle α (i.e., when α>0°) causes thegas to flow in a circular direction as shown by arrows 310A and 310B.Providing gas at an angle a as opposed to directly straight-on to thewalls of the expanding channel (i.e., when α=0°) helps to provide a morelaminar flow through the expanding channel 234 rather than a turbulentflow. It is believed that a laminar flow through the expanding channel234 results in an improved purging of the inner surface of the expandingchannel 234 and other surfaces of the chamber lid 232. In comparison, aturbulent flow may not uniformly flow across the inner surface of theexpanding channel 234 and other surfaces and may contain dead spots orstagnant spots in which there is no gas flow. In one aspect, the gasconduits 250A, 250B and the corresponding gas inlets 236A, 236B arespaced out from each other and direct a flow in the same circulardirection (i.e., clockwise or counter-clockwise).

Not wishing to be bound by theory, FIG. 3 is a cross-sectional view ofthe expanding channel 234 of a chamber lid 232 showing simplifiedrepresentations of two gas flows therethrough. Although the exact flowpattern through the expanding channel 234 is not known, it is believedthat the circular flow 310 (FIG. 2, arrows 310A and 310B) may travel asa “vortex,” “helix,” or “spiral” flow through the expanding channel 234as shown by arrows 402A, 402B (hereinafter “vortex” flow 402). As shownin FIG. 3, the circular flow may be provided in a “processing region” asopposed to in a compartment separated from the substrate 210. In oneaspect, the vortex flow may help to establish a more efficient purge ofthe expanding channel 234 due to the sweeping action of the vortex flowpattern across the inner surface of the expanding channel 234.

In one embodiment, the distance 410 between the gas inlets 236A, 236Band the substrate 210 is made long enough that the “vortex” flow 402dissipates to a downwardly flow as shown by arrows 404 as a spiral flowacross the surface of the substrate 210 may not be desirable. It isbelieved that the “vortex” flow 402 and the downwardly flow 404 proceedin a laminar manner efficiently purging the surface of the chamber lid232 and the substrate 210. In one specific embodiment the distance 410between the upper portion 237 of the expanding channel 234 and thesubstrate 210 is about 1.0 inch or more, more preferably about 2.0inches or more. In one specific embodiment, the upper limit of thedistance 410 is dictated by practical limitations. For example, if thedistance 410 is very long, then the residence time of a gas travelingthough the expanding channel 234 would be long, then the time for a gasto deposit onto the substrate would be long, and then throughput wouldbe low. In addition, if distance 410 is very long, manufacturing of theexpanding channel 234 would be difficult. In general, the upper limit ofdistance 410 may be 3 inches or more for a chamber adapted to process200 mm diameter substrates or 5 inches or more for a chamber adapted toprocess 300 mm diameter substrates.

Referring to FIG. 1, at least a portion of the bottom surface 260 of thechamber lid 232 may be tapered from the expanding channel 234 to aperipheral portion of the chamber lid 232 to help provide an improvedvelocity profile of a gas flow from the expanding channel 234 across thesurface of the substrate 210 (i.e., from the center of the substrate tothe edge of the substrate). The bottom surface 260 may comprise one ormore tapered surfaces, such as a straight surface, a concave surface, aconvex surface, or combinations thereof. In one embodiment, the bottomsurface 260 is tapered in the shape of a funnel.

Not wishing to be bound by theory, FIG. 4 is schematic view illustratingthe flow of a gas at two different positions 502, 504 between the bottomsurface 260 of the chamber lid 232 and the surface of a substrate 210.The velocity of the gas at a certain position is theoreticallydetermined by the equation below:Q/A=V  (1)In which, “Q” is the flow of the gas, “A” is the area of the flowsection, and “V” is the velocity of the gas. The velocity of the gas isinversely proportional to the area “A” of the flow section (H_(x)2πR),in which “H” is the height of the flow section and 2π“R” is thecircumference of the flow section having a radius “H”. In other words,the velocity of a gas is inversely proportional to the height “H” of theflow section and the radius “R” of the flow section.

Comparing the velocity of the flow section at position 502 and position504, assuming that the flow “Q” of the gas at all positions between thebottom surface 260 of the chamber lid 232 and the surface of thesubstrate 210 is equal, the velocity of the gas may be theoreticallymade equal by having the area “A” of the flow sections equal. For thearea of flow sections at position 502 and position 504 to be equal, theheight H₁ at position 502 must be greater than the height H₂ at position504.

In one aspect, the bottom surface 260 is downwardly sloping to helpreduce the variation in the velocity of the gases as it travels betweenthe bottom surface 260 of the chamber lid 232 and the substrate 210 tohelp provide uniform exposure of the surface of the substrate 210 to areactant gas. In one embodiment, the ratio of the maximum area of theflow section over the minimum area of the flow section between adownwardly sloping bottom surface 260 of the chamber lid 232 and thesurface of the substrate 210 is less than about 2, preferably less thanabout 1.5, more preferably less than about 1.3, and most preferablyabout 1.

Not wishing to be bound by theory, it is believed that a gas flowtraveling at a more uniform velocity across the surface of the substrate210 helps provide a more uniform deposition of the gas on the substrate210. It is believed that the velocity of the gas is directlyproportional to the concentration of the gas which is in turn directlyproportional to the deposition rate of the gas on the substrate 210surface. Thus, a higher velocity of a gas at a first area of the surfaceof the substrate 210 versus a second area of the surface of thesubstrate 210 is believed to provide a higher deposition of the gas onthe first area. It is believed that a chamber lid 232 having adownwardly sloping bottom surface 260 provides for more uniformdeposition of the gas across the surface of the substrate 210 becausethe downwardly sloping bottom surface 260 provides a more uniformvelocity and, thus, a more uniform concentration of the gas across thesurface of the substrate 210.

Referring to FIG. 1, the chamber lid 232 may have a choke 262 at aperipheral portion of the chamber lid 232 adjacent the periphery of thesubstrate 210. The choke 262, when the chamber lid 232 is assembled toform a processing zone around the substrate 210, comprises any memberrestricting the flow of gas therethrough at an area adjacent theperiphery of the substrate 210. FIG. 9A is a schematic cross-sectionalview of one embodiment of the choke 262. In this embodiment, the choke262 comprises a circumferential lateral portion 267. In one aspect, thepurge ring 222 may be adapted to direct a purge gas toward the lateralportion 267 of the choke 262. FIG. 9B is a schematic cross-sectionalview of another embodiment of the choke 262. In this embodiment, thechoke 262 comprises a circumferential downwardly extending protrusion268. In one aspect, the purge ring 222 may be adapted to direct a purgegas toward the circumferential downwardly extending protrusion 268. Inone specific embodiment, the thickness of the downwardly extendingprotrusion 268 is between about 0.01 inches and about 1.0 inch, morepreferably between 0.01 inches and 0.5 inches.

In one specific embodiment, the spacing between the choke 262 and thesubstrate support 212 is between about 0.04 inches and about 2.0 inches,and preferably between 0.04 inches and about 0.2 inches. The spacing mayvary depending on the gases being delivered and the process conditionsduring deposition. The choke 262 helps provide a more uniform pressuredistribution within the volume or a reaction zone 264 defined betweenthe chamber lid 232 and the substrate 210 by isolating the reaction zone264 from the non-uniform pressure distribution of the pumping zone 266(FIG. 1).

Referring to FIG. 1, in one aspect, since the reaction zone 264 isisolated from the pumping zone 266, a reactant gas or purge gas needsonly adequately fill the reaction zone 264 to ensure sufficient exposureof the substrate 210 to the reactant gas or purge gas. In conventionalchemical vapor deposition, prior art chambers are required to provide acombined flow of reactants simultaneously and uniformly to the entiresurface of the substrate in order to ensure that the co-reaction of thereactants occurs uniformly across the surface of the substrate 210. Inatomic layer deposition, the present chamber 200 sequentially introducesreactants to the surface of substrate 210 to provide absorption ofalternating thin layers of the reactants onto the surface of thesubstrate 210. As a consequence, atomic layer deposition does notrequire a flow of a reactant which reaches the surface of the substrate210 simultaneously. Instead, a flow of a reactant needs to be providedin an amount which is sufficient to adsorb a thin layer of the reactanton the surface of the substrate 210.

Since the reaction zone 264 may comprise a smaller volume when comparedto the inner volume of a conventional CVD chamber, a smaller amount ofgas is required to fill the reaction zone 264 for a particular processin an atomic layer deposition sequence. For example, in one embodiment,the volume of the reaction zone 264 is about 1,000 cm³ or less,preferably 500 cm³ or less, and more preferably 200 cm³ or less for achamber adapted to process 200 mm diameter substrates. In oneembodiment, the volume of the reaction zone 264 is about 3,000 cm³ orless, preferably 1,500 cm³ or less, and more preferably 600 cm³ or lessfor a chamber adapted to process 300 mm diameter substrates. In oneembodiment, the substrate support 212 may be raised or lowered to adjustthe volume of the reaction zone 264 for deposition. Because of thesmaller volume of the reaction zone 264, less gas, whether a depositiongas or a purge gas, is necessary to be flowed into the chamber 200.Therefore, the throughput of the chamber 200 is greater and the wastemay be minimized due to the smaller amount of gas used reducing the costof operation.

The chamber lid 232 has been shown in FIGS. 1-4 as comprising a capportion 272 and a chamber plate portion 270 in which the cap portion 272and the chamber plate portion 270 form the expanding channel 234. Anadditional plate may be optionally disposed between the chamber plateportion 270 and the cap portion 272. In other embodiments, the expandingchannel 234 may be made integrally from a single piece of material.

The chamber lid 232 may include cooling elements and/or heating elementsdepending on the particular gas being delivered therethrough.Controlling the temperature of the chamber lid 232 may be used toprevent gas decomposition, deposition, or condensation on the chamberlid 232. For example, water channels (not shown) may be formed in thechamber lid 232 to cool the chamber lid 232. In another example, heatingelements (not shown) may be embedded or may surround components of thechamber lid 232 to heat the chamber lid 232. In one embodiment,components of the chamber lid 232 may be individually heated or cooled.For example, referring to FIG. 1, the chamber lid 232 may comprise achamber plate portion 270 and a cap portion 272 in which the chamberplate portion 270 and the cap portion 272 form the expanding channel234. The cap portion 272 may be maintained at one temperature range andthe chamber plate portion 270 may be maintained at another temperaturerange. For example, the cap portion 272 may be heated by being wrappedin heater tape or by using another heating device to preventcondensation of reactant gases and the chamber plate portion 270 may bemaintained at ambient temperature. In another example, the cap portion272 may be heated and the chamber plate portion 270 may be cooled withwater channels formed therethrough to prevent thermal decomposition ofreactant gases on the chamber plate portion 270.

The chamber lid 232 may be made of stainless steel, aluminum,nickel-plated aluminum, nickel, or other suitable materials compatiblewith the processing to be performed. In one embodiment, the cap portion272 comprises stainless steel and the chamber plate portion 270comprises aluminum. In one embodiment, the optional additional platedisposed therebetween comprises stainless steel. In one embodiment, theexpanding channel 234 and the bottom surface 260 of the chamber lid 232may comprise a mirror polished surface to help produce a laminar flow ofa gas along the expanding channel 234 and the bottom surface 260 of thechamber lid 232. In another embodiment, the inner surface of the gasconduits 250A, 250B may be electropolished to help produce a laminarflow of a gas therethrough.

Returning to FIG. 1, a control unit 280, such as a programmed personalcomputer, work station computer, or the like, may be coupled to thechamber 200 to control processing conditions. For example, the controlunit 280 may be configured to control flow of various process gases andpurge gases from gas sources 238, 239, 240 through the valves 242A, 242Bduring different stages of a substrate process sequence. Illustratively,the control unit 280 comprises a central processing unit (CPU) 282,support circuitry 284, and memory 286 containing associated controlsoftware 283.

The control unit 280 may be one of any form of general purpose computerprocessor that can be used in an industrial setting for controllingvarious chambers and subprocessors. The CPU 282 may use any suitablememory 286, such as random access memory, read only memory, floppy diskdrive, hard disk, or any other form of digital storage, local or remote.Various support circuits may be coupled to the CPU 282 for supportingthe chamber 200. The control unit 280 may be coupled to anothercontroller that is located adjacent individual chamber components, suchas the programmable logic controllers 248A, 248B of the valves 242A,242B. Bi-directional communications between the control unit 280 andvarious other components of the chamber 200 are handled through numeroussignal cables collectively referred to as signal buses 288, some ofwhich are illustrated in FIG. 1. In addition to control of process gasesand purge gases from gas sources 238, 239, 240 and from the programmablelogic controllers 248A, 248B of the valves 242A, 242B, the control unit280 may be configured to be responsible for automated control of otheractivities used in wafer processing-such as wafer transport, temperaturecontrol, chamber evacuation, among other activities, some of which aredescribed elsewhere herein.

Referring to FIGS. 1-4, in operation, a substrate 210 is delivered tothe chamber 200 through the slit valve 208 by a robot (not shown). Thesubstrate 210 is positioned on the substrate support 212 throughcooperation of the lift pins 220 and the robot. The substrate support212 raises the substrate 210 into close opposition to the bottom surface260 of the chamber lid 232. A first gas flow may be injected into theexpanding channel 234 of the chamber 200 by valve 242A together orseparately (i.e., pulses) with a second gas flow injected into thechamber 200 by valve 242B. The first gas flow may comprise a continuousflow of a purge gas from purge gas source 240 and pulses of a reactantgas from reactant gas source 238 or may comprise pulses of a reactantgas from reactant gas source 238 and pulses of a purge gas from purgegas source 240. The second gas flow may comprises a continuous flow of apurge gas from purge gas source 240 and pulses of a reactant gas fromreactant gas source 239 or may comprise pulses of a reactant gas fromreactant gas source 239 and pulses of a purge gas from purge gas source240. The gas flow travels through the expanding channel 234 as a patternof vortex flow 402 which provides a sweeping action across the innersurface of the expanding channel 234. The pattern of vortex flow 402dissipates to a downwardly flow 404 toward the surface of the substrate210. The velocity of the gas flow reduces as it travels through theexpanding channel 234. The gas flow then travels across the surface ofthe substrate 210 and across the bottom surface 260 of the chamber lid232. The bottom surface 260 of the chamber lid 232, which is downwardlysloping, helps reduce the variation of the velocity of the gas flowacross the surface of the substrate 210. The gas flow then travels bythe choke 262 and into the pumping zone 266 of the chamber 200. Excessgas, by-products, etc. flow into the pumping channel 279 and are thenexhausted from the chamber 200 by a vacuum system 278. In one aspect,the gas flow proceeds through the expanding channel 234 and between thesurface of the substrate 210 and the bottom surface 260 of the chamberlid 232 in a laminar manner which aids in uniform exposure of a reactantgas to the surface of the substrate 210 and efficient purging of innersurfaces of the chamber lid 232.

Chamber 200 as illustrated in FIGS. 1-4 has been described herein ashaving a combination of features. In one aspect, chamber 200 provides areaction zone 264 comprising a small volume in compared to aconventional CVD chamber. The chamber 200 requires a smaller amount of agas, such as a reactant gas or a purge gas, to fill the reaction zone264 for a particular process. In another aspect, chamber 200 provides achamber lid 232 having a downwardly sloping or funnel shaped bottomsurface 260 to reduce the variation in the velocity profile of a gasflow traveling between the bottom surface of the chamber lid 232 and asubstrate 210. In still another aspect, the chamber 200 provides anexpanding channel 234 to reduce the velocity of a gas flow introducedtherethrough. In still another aspect, the chamber 200 provides gasconduits at an angle a from the center of the expanding channel 234. Thechamber 200 provides other features as described elsewhere herein. Otherembodiments of a chamber adapted for atomic layer deposition incorporateone or more of these features.

For example, FIG. 7 shows another embodiment of a chamber 800 includinga gas delivery apparatus 830 comprising a chamber lid 832 which providesa reaction zone 864 comprising a small volume and which provides anexpanding channel 834. Some components of the chamber 800 are the sameor similar to those described with reference to chamber 200 of FIG. 1,described above. Accordingly, like numbers have been used whereappropriate. The chamber lid 832 comprises a bottom surface 860 that issubstantially flat. In one embodiment, the spacing between the choke 262and the substrate support 212 is between about 0.04 inches and about 2.0inches, more preferably between about 0.04 inches and about 0.2 inches.

In another example, FIG. 8 shows another embodiment of a chamber 900including a gas delivery apparatus 930 comprising a chamber lid 932which provides a reaction zone 964 comprising a small volume and whichprovides a downwardly sloping or funnel shaped bottom surface 960. Somecomponents of the chamber 900 are the same or similar to those describedwith reference to chamber 200 of FIG. 1, described above. Accordingly,like numbers have been used where appropriate. Gas sources 937 arecoupled to the passageway 933 through one or more valves 941. In oneaspect, the passageway 933 comprises a long length to reduce thelikelihood that a gas introduced through valves 941 will blow offreactants adsorbed on the surface of the substrate 210.

The gas delivery apparatuses 230, 830, 930 of FIGS. 1-8 have beendescribed above as comprising chamber lids 232, 832, 932 which act asthe lid of the chamber body 202. Other embodiments of the chamber lids232, 832, 932 comprises any covering member disposed over the substratesupport 212 delineating a reaction zone 264, 864, 964 which lowers thevolume in which a gas must flow during substrate processing. In otherembodiments, instead of or in conjunction with the substrate support212, the chamber lid 232, 832, 932 may be adapted to move up and down toadjust the volume of the reaction zone 264, 864, 964.

The gas delivery apparatus 230 of FIG. 1 has been described as includingtwo pairs of valves 242A/252A, 242B/252B coupled to a reactant gassource 238, 239 and a purge gas source 240. In other embodiments, thegas delivery apparatus 230 may comprise one or more valves coupled to asingle or a plurality of gas sources in a variety of configurations.FIGS. 1-3 show a chamber 200 adapted to provide two gas flows togetheror separately from two gas inlets 236A, 236B utilizing two pairs ofvalves 242A/252A, 242B/252B. FIG. 5 is a top cross-sectional view ofanother embodiment of an expanding channel 634 of the chamber lid 232which is adapted to receive a single gas flow through one gas inlet 636from one gas conduit 650 coupled to a single or a plurality of valves.The gas conduit 650 may be positioned at an angle α from the center line602 of the gas conduit 650 and from a radius line 604 from the center ofthe expanding channel 634. The gas conduit 650 positioned at an angle α(i.e., when α>0°) causes a gas to flow in a circular direction as shownby arrow 610. FIG. 6 is a top cross-sectional view of another embodimentof an expanding channel 734 of the chamber lid 232 which is adapted toreceive three gas flows together, partially together (i.e., two of threegas flows together), or separately through three gas inlets 736A, 736B,736C from three gas conduits 750A, 750B, 750C in which each conduit iscoupled to a single or a plurality of valves. The gas conduits 750A,750B, 750C may be positioned at an angle α from the center line 702 ofthe gas conduits 750A, 750B, 750C and from a radius line 704 from thecenter of the expanding channel 734. The gas conduits 750A, 750B, 750Cpositioned at an angle α (i.e., when α>0°) causes a gas to flow in acircular direction as shown by arrows 710.

Embodiments of chambers 200, 800, 900 with gas delivery apparatuses 230,830, 930 as described in FIGS. 1-8 may be used advantageously toimplement atomic layer deposition processes of elements, which includebut are not limited to, tantalum, titanium, tungsten, and copper, or toimplement atomic layer deposition of compounds or alloys/combinationsfilms, which include but are not limited to tantalum nitride, tantalumsilicon nitride, titanium nitride, titanium silicon nitride, tungstennitride, tungsten silicon nitride, and copper aluminum. Embodiments ofchambers 200, 800, 900 with gas delivery apparatuses 230, 830, 930 asdescribed in FIGS. 1-8 may also be used advantageously to implementchemical vapor deposition of various materials.

For clarity reasons, deposition of a layer by atomic layer depositionwill be described in more detail in reference to the atomic layerdeposition of a tantalum nitride layer utilizing chamber 200 asdescribed in FIGS. 1-4. In one aspect, atomic layer deposition of atantalum nitride barrier layer comprises sequentially providing pulsesof a tantalum containing compound and pulses of a nitrogen containingcompound to the process chamber 200 in which each pulse is separated bya flow of a purge gas and/or chamber evacuation to remove any excessreactants to prevent gas phase reactions of the tantalum containingcompound with the nitrogen containing compound and to remove anyreaction by-products. Sequentially providing a tantalum containingcompound and a nitrogen containing compound may result in thealternating absorption of monolayers of a tantalum containing compoundand of monolayers of a nitrogen containing compound to form a monolayerof tantalum nitride on a substrate structure for each cycle of pulses.The term substrate structure is used to refer to the substrate as wellas other material layers formed thereover, such as a dielectric layer.

It is believed that the adsorption processes used to adsorb themonolayer of the reactants, such as the tantalum containing compound andthe nitrogen containing compound, are self-limiting in that only onemonolayer may be adsorbed onto the surface of the substrate structureduring a given pulse because the surface of the substrate structure hasa finite number of sites for adsorbing the reactants. Once the finitenumber of sites is occupied by the reactants, such as the tantalumcontaining compound or the nitrogen containing compound, furtherabsorption of the reactants will be blocked. The cycle may be repeatedto a desired thickness of the tantalum nitride layer.

Pulses of a tantalum containing compound, such aspentakis(dimethylamido) tantalum (PDMAT; Ta(NMe₂)₅), may be introducedby gas source 238 through valve 242A. The tantalum containing compoundmay be provided with the aid of a carrier gas, which includes, but isnot limited to, helium (He), argon (Ar), nitrogen (N₂), hydrogen (H₂),and combinations thereof. Pulses of a nitrogen containing compound, suchas ammonia, may be introduced by gas source 239 through valve 242A. Acarrier gas may also be used to help deliver the nitrogen containingcompound. A purge gas, such as argon, may be introduced by gas source240 through valve 242A and/or through valve 242B. In one aspect, theflow of purge gas may be continuously provided by gas source 240 throughvalves 242A, 242B to act as a purge gas between the pulses of thetantalum containing compound and of the nitrogen containing compound andto act as a carrier gas during the pulses of the tantalum containingcompound and the nitrogen containing compound. In one aspect, deliveringa purge gas through two gas conduits 250A, 250B provides a more completepurge of the reaction zone 264 rather than a purge gas provided throughone gas conduit 250A, 250B. In one aspect, a reactant gas may bedelivered through one gas conduit 250A, 250B since uniformity of flow ofa reactant gas, such as a tantalum containing compound or a nitrogencontaining compound, is not as critical as uniformity of the purge gasdue to the self-limiting absorption process of the reactants on thesurface of substrate structures. In other embodiments, a purge gas maybe provided in pulses. In other embodiments, a purge gas may be providedin more or less than two gas flows. In other embodiments, a tantalumcontaining gas may be provided in more than a single gas flow (i.e., twoor more gas flows). In other embodiments, a nitrogen containing may beprovided in more than a single gas flow (i.e., two or more gas flows).

Other examples of tantalum containing compounds, include, but are notlimited to, other organometallic precursors or derivatives thereof, suchas pentakis(ethylmethylamido) tantalum (PEMAT; Ta(N(Et)Me)₅),pentakis(diethylamido) tantalum (PDEAT; Ta(NEt₂)₅,), and any and allderivatives of PEMAT, PDEAT, or PDMAT. Other tantalum containingcompounds include without limitation tertbutylimido tris(diethylamido)tantalum (TBTDET; Ta(NEt₂)₃NC₄H₉; or C₁₆H₃₉N₄Ta), and tantalum halides,for example TaX₅ where X is fluorine (F), bromine (Br) or chlorine (Cl),and/or derivatives thereof. Other nitrogen containing compounds may beused which include, but are not limited to, N_(x)H_(y) with x and ybeing integers (e.g., hydrazine (N₂H₄)), dimethyl hydrazine((CH₃)₂N₂H₂), tertbutylhydrazine (C₄H₉N₂H₃), phenylhydrazine (C₆H₅N₂H₃),other hydrazine derivatives, a nitrogen plasma source (e.g., N₂, N₂/H₂,NH₃, or a N₂H₄ plasma), 2,2′-azotertbutane ((CH₃)₆C₂N₂), ethylazide(C₂H₅N₃), and other suitable gases. Other examples of purge gasesinclude, but are not limited to, helium (He), nitrogen (N₂), hydrogen(H₂), other gases, and combinations thereof.

The tantalum nitride layer formation is described as starting with theabsorption of a monolayer of a tantalum containing compound on thesubstrate followed by a monolayer of a nitrogen containing compound.Alternatively, the tantalum nitride layer formation may start with theabsorption of a monolayer of a nitrogen containing compound on thesubstrate followed by a monolayer of the tantalum containing compound.Furthermore, in other embodiments, a pump evacuation alone betweenpulses of reactant gases may be used to prevent mixing of the reactantgases.

The time duration for each pulse of the tantalum containing compound,the time duration for each pulse of the nitrogen containing compound,and the duration of the purge gas flow between pulses of the reactantsare variable and depend on the volume capacity of a deposition chamberemployed as well as a vacuum system coupled thereto. For example, (1) alower chamber pressure of a gas will require a longer pulse time; (2) alower gas flow rate will require a longer time for chamber pressure torise and stabilize requiring a longer pulse time; and (3) a large-volumechamber will take longer to fill, longer for chamber pressure tostabilize thus requiring a longer pulse time. Similarly, time betweeneach pulse is also variable and depends on volume capacity of theprocess chamber as well as the vacuum system coupled thereto. Ingeneral, the time duration of a pulse of the tantalum containingcompound or the nitrogen containing compound should be long enough forabsorption of a monolayer of the compound. In one aspect, a pulse of atantalum containing compound may still be in the chamber when a pulse ofa nitrogen containing compound enters. In general, the duration of thepurge gas and/or pump evacuation should be long enough to prevent thepulses of the tantalum containing compound and the nitrogen containingcompound from mixing together in the reaction zone.

Generally, a pulse time of about 1.0 second or less for a tantalumcontaining compound and a pulse time of about 1.0 second or less for anitrogen containing compound are typically sufficient to adsorbalternating monolayers on a substrate structure. A time of about 1.0second or less between pulses of the tantalum containing compound andthe nitrogen containing compound is typically sufficient for the purgegas, whether a continuous purge gas or a pulse of a purge gas, toprevent the pulses of the tantalum containing compound and the nitrogencontaining compound from mixing together in the reaction zone. Ofcourse, a longer pulse time of the reactants may be used to ensureabsorption of the tantalum containing compound and the nitrogencontaining compound and a longer time between pulses of the reactantsmay be used to ensure removal of the reaction by-products.

During atomic layer deposition, the substrate 210 may be maintainedapproximately below a thermal decomposition temperature of a selectedtantalum containing compound. An exemplary heater temperature range tobe used with tantalum containing compounds identified herein isapproximately between about 20° C. and about 500° C. at a chamberpressure less than about 100 Torr, preferably less than 50 Torr. Whenthe tantalum containing gas is PDMAT, the heater temperature ispreferably between about 100° C. and about 300° C., more preferablybetween about 175° C. and 250° C., and the chamber pressure is betweenabout 1.0 Torr and about 5.0 Torr. In other embodiments, it should beunderstood that other temperatures and pressures may be used. Forexample, a temperature above a thermal decomposition temperature may beused. However, the temperature should be selected so that more than 50percent of the deposition activity is by absorption processes. Inanother example, a temperature above a thermal decomposition temperaturemay be used in which the amount of decomposition during each precursordeposition is limited so that the growth mode will be similar to anatomic layer deposition growth mode.

One exemplary process of depositing a tantalum nitride layer by atomiclayer deposition, in the process chamber 200 of FIGS. 1-4, comprisesproviding pulses of pentakis(dimethylamido) tantalum (PDMAT) from gassource 238 at a flow rate between about 100 sccm and about 1,000 sccm,preferably between about 100 sccm and about 400 sccm, through valve 242Afor a pulse time of about 0.5 seconds or less, about 0.1 seconds orless, or about 0.05 seconds or less due the smaller volume of thereaction zone 264. Pulses of ammonia may be provided from gas source 239at a flow rate between about 100 sccm and about 1,000 sccm, preferablybetween 200 sccm and about 600 sccm, through valve 242B for a pulse timeof about 0.5 seconds or less, about 0.1 seconds or less, or about 0.05seconds or less due to a smaller volume of the reaction zone 264. Anargon purge gas at a flow rate between about 100 sccm and about 1,000sccm, preferably, between about 100 sccm and about 400 sccm, may becontinuously provided from gas source 240 through valves 242A, 242B. Thetime between pulses of the tantalum containing compound and the nitrogencontaining compound may be about 0.5 seconds or less, about 0.1 secondsor less, or about 0.07 seconds or less due to the smaller volume of thereaction zone 264. It is believed that a pulse time of about 0.016seconds or more is required to fill the reaction zone 264 with areactant gas and/or a purge gas. The heater temperature preferably ismaintained between about 100° C. and about 300° C. at a chamber pressurebetween about 1.0 Torr and about 5.0 Torr. This process provides atantalum nitride layer in a thickness between about 0.5 Å and about 1.0Å per cycle. The alternating sequence may be repeated until a desiredthickness is achieved.

In one embodiment, the layer, such as a tantalum nitride layer, isdeposited to a sidewall coverage of about 50 Å or less. In anotherembodiment, the layer is deposited to a sidewall coverage of about 20 Åor less. In still another embodiment, the layer is deposited to asidewall coverage of about 10 Å or less. A tantalum nitride layer with athickness of about 10 Å or less is believed to be a sufficient thicknessin the application as a barrier layer to prevent copper diffusion. Inone aspect, a thin barrier layer may be used to advantage in fillingsubmicron (e.g., less than 0.15 μm) and smaller features having highaspect ratios (e.g., greater than 5 to 1). Of course, a layer having asidewall coverage of greater than 50 Å may be used.

Embodiments of atomic layer deposition have been described above asabsorption of a monolayer of reactants on a substrate. The presentinvention also includes embodiments in which the reactants are depositedto more or less than a monolayer. The present invention also includesembodiments in which the reactants are not deposited in a self-limitingmanner. The present invention also includes embodiments in whichdeposition occurs in mainly a chemical vapor deposition process in whichthe reactants are delivered sequentially or simultaneously.

Embodiments of atomic layer deposition have been described above as thedeposition of the binary compound of tantalum nitride utilizing pulsesof two reactants. In the deposition of other elements or compounds,pulses of two or more reactants may also be used.

While foregoing is directed to the preferred embodiment of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method for depositing a material layer on a substrate surface,comprising: positioning a substrate on a substrate support within aprocess chamber comprising a chamber body and a chamber lid, wherein thechamber lid comprises: an expanding channel at a central portion of thechamber lid; a tapered bottom surface extending from the expandingchannel to a peripheral portion of the chamber lid, wherein the taperedbottom surface is shaped and sized to substantially cover the substrate;a first conduit coupled to a first gas inlet; and a second conduitcoupled to a second gas inlet, wherein the first and second gas inletsare in fluid communication with the expanding channel, and the first andsecond conduits are positioned to provide a gas flow comprising acircular pattern within the expanded channel; flowing a carrier gas intothe expanding channel to form a circular flow of the carrier gas;exposing the substrate to the circular flow of the carrier gas; pulsinga first reactant gas into the circular flow of the carrier gas from thefirst gas inlet; and depositing a material onto the substrate.
 2. Themethod of claim 1, further comprising pulsing a second reactant gas intothe circular flow of the carrier gas from the second gas inlet.
 3. Themethod of claim 1, wherein the circular flow of the carrier gascomprises a gas flow pattern selected from the group consisting ofvortex, helix, spiral, and derivatives thereof.
 4. The method of claim3, wherein the carrier gas comprises a gas selected from the groupconsisting of argon, nitrogen, hydrogen, helium, and combinationsthereof.
 5. The method of claim 1, wherein the deposited materialcomprises tantalum, titanium, tungsten, copper, alloys thereof, orcombinations thereof.
 6. The method of claim 5, wherein the depositedmaterial comprises tantalum nitride, tantalum silicon nitride, titaniumnitride, titanium silicon nitride, tungsten nitride, tungsten siliconnitride, copper aluminum, alloys thereof, or combinations thereof. 7.The method of claim 3, wherein the deposited material comprises tungstenor tungsten nitride.
 8. The method of claim 2, wherein the depositedmaterial comprises tantalum nitride.
 9. The method of claim 8, whereinthe first reactant gas comprises a tantalum precursor selected from thegroup consisting of pentakis(dimethylamido) tantalum,pentakis(diethylamido) tantalum, pentakis(ethylmethylamido) tantalum,tertbutylimido tris(diethylamido) tantalum, and derivatives thereof. 10.The method of claim 8, wherein the second reactant gas comprises anitrogen precursor selected from the group consisting of ammonia,hydrazine, dimethylhydrazine, tertbutylhydrazine, a nitrogen plasmasource, and derivatives thereof.
 11. The method of claim 10, wherein thenitrogen plasma source comprises nitrogen, a nitrogen and hydrogenmixture, ammonia, or hydrazine.
 12. The method of claim 8, wherein thefirst reactant gas comprises pentakis(dimethylamido) tantalum and thesecond reactant gas comprises ammonia.
 13. A method for depositing amaterial layer on a substrate surface, comprising: positioning asubstrate on a substrate support within a process chamber comprising achamber body and a chamber lid, wherein the chamber lid comprises: anexpanding channel at a central portion of the chamber lid; a taperedbottom surface extending from the expanding channel to a peripheralportion of the chamber lid, wherein the tapered bottom surface is shapedand sized to substantially cover the substrate; a first conduit coupledto a first gas inlet; and a second conduit coupled to a second gasinlet, wherein the first and second gas inlets are in fluidcommunication with the expanding channel, and the first and secondconduits are positioned to provide a gas flow comprising a circularpattern within the expanded channel; flowing a first reactant gas fromthe first gas inlet; flowing a second reactant gas from the second gasinlet; and exposing the substrate sequentially to the first and secondreactant gases to deposit a material onto the substrate, wherein thefirst and second reactant gases comprise a circular gas flow.
 14. Themethod of claim 13, wherein the circular gas flow comprises a gas flowpattern selected from the group consisting of vortex, helix, spiral, andderivatives thereof.
 15. A method for depositing a material layer on asubstrate surface, comprising: positioning a substrate on a substratesupport within a process chamber comprising a gas delivery systemenabled to form a gas flow comprising a circular pattern; flowing acarrier gas into the process chamber while forming a circular flow ofthe carrier gas; exposing the substrate to the circular flow of thecarrier gas; pulsing a first reactant gas into the circular flow of thecarrier gas; and depositing a material onto the substrate.
 16. Themethod of claim 15, further comprising pulsing a second reactant gasinto the circular flow of the carrier gas.
 17. The method of claim 15,wherein the circular flow of the carrier gas comprises a gas flowpattern selected from the group consisting of vortex, helix, spiral, andderivatives thereof.
 18. The method of claim 17, wherein the depositedmaterial comprises tantalum, titanium, tungsten, copper, alloys thereof,or combinations thereof.
 19. The method of claim 18, wherein thedeposited material comprises tungsten or tungsten nitride.
 20. Themethod of claim 18, wherein the deposited material comprises tantalumnitride.